a. Field of the Invention
The invention relates to a display device, particularly to a display device having two different viewing angles.
b. Description of the Related Art
FIG. 1 shows a schematic diagram of a conventional display device having two different viewing angles. The display device may provide two different images respectively for different viewers at the same time because of the different viewing angles. The solid lines in FIG. 1 represent images prepared for a right-side viewer, and the dashed lines represent images prepared for a left-side viewer. As shown in FIG. 1, a display panel 102 serves as an images source, a backlight 104 provides a planar light source emitting light at different directions, and a parallax barrier element 106 is disposed to control the light-emitting direction. By adjusting a width of a light output area 106a of the parallax barrier element 106, a spacing between two adjacent light output areas 106a, and a relative position of the parallax barrier element 106 and the display panel 102, an appropriate light-emitting angle is obtained to allow the right-side viewer to see the images R1, R3, R5, and R7 and the left-side viewer to see the images L2, L4, L6, and L8. That is, two different images are provided for viewers at different positions. However, by such a design, the right-side viewer and the left-side viewer may view an image with half resolution.
Therefore, another design is proposed to provide a synchronization device 108 capable of performing timing and synchronization controls over the parallax barrier element 106 and the display panel 102. Specifically, at a first time point, the synchronization device 108 simultaneously controls the parallax barrier element 106 and the display panel 102 to allow the right-side viewer to see the images R1, R3, R5, and R7 and the left-side viewer to see the images L2, L4, L6, and L8, as shown in FIG. 1. At a subsequent time point, the synchronization device 108 simultaneously controls the parallax barrier element 106 and the display panel 102 to allow the right-side viewer to see the images R2, R4, R6, and R8 and the left-side viewer to see the images L1, L3, L5, and L7, as shown in FIG. 2. Under the circumstance, because of persistence of vision, the switch of the synchronization device 108 enables the right-side viewer and the left-side viewer to see a full resolution frame (including images R1, R2, R3, R4, R5, R6, R7, and R8 for the right-side viewer or images L1, L2, L3, L4, L5, L6, L7, and L8 for the left-side viewer).
However, the conventional designs use the parallax barrier element 106 to control viewing angles, and such configuration may result in an increase in thickness, weight, and fabrication costs. Further, the parallax barrier element 106 and the display panel 102 need to be aligned precisely to achieve the effect of controlling viewing angles to thereby increase the assembly complexity and decrease the production yield.